This invention relates to propeller blades designed to aerodynamically generate thrust and more particularly to propeller blades used on hovercraft, airboats, dirigibles, or other vehicles requiring maximum thrust at static or low vehicle velocities.
Existing fixed-wing propeller blades and helicopter rotor blades must meet the operational requirements of take-off, climb, cruise, and, in the case of helicopters, autorotation. As a result, current blades are designed to efficiently move aircraft at the relatively high airspeeds necessary to maintain flight. These prior art blades, however, have failed to effectively and efficiently develop the thrust needed to meet the design parameters for vehicles such as hovercraft.
One major drawback of conventional propellers and rotors is the lack of thrust developed at static velocities. This is due to current blade configurations that operate in an over-80-percent-stalled condition at zero velocity. In addition, current blades cannot generate the reverse thrust that hovercraft require to reduce speed, reverse direction, or maneuver. Another significant problem is poor environmental durability. The sand and dust particles, as well as water droplets, which are present around hovercraft operating low to the surface, quickly erode the leading edges and tips of low-profile, high-aspect ratio blades. Finally, prior art blades generally high noise levels due to blade tip speed.